Filtration devices and methods are known and used in a variety of industries, including pharmaceutical, biotechnology, food processing and packaging, oil and gas industries etc. For example, membrane filtration devices have been used to eliminate undesirable impurities and other potentially harmful contaminants from end products in pharmaceutical and biotechnology industries.
To ensure that filtration devices comply with desired performance criteria, the integrity of the filtration devices is routinely tested before and/or after use. Integrity testing determines if a filtration device is free of defects or breaches in the membrane or porous material of the filtration device exceeding a desired size limitation, which would impair the device function and thus allow the end product to become contaminated with harmful or undesirable materials.
Integrity testing of filtration devices can be destructive or non-destructive. Destructive test is typically performed as a lot release criteria on samples from manufacturing lots of fabricated filter products. In a destructive test, a filter product is challenged with bacteria to determine the filter's ability to retain the bacteria. The test is “destructive” because it renders the filter unusable for actual application. Non-destructive test is routinely conducted on each filter device before and after use. The stringent requirements of the pharmaceutical industry dictate that non-destructive tests on filter devices must be performed in each sterilizing application at the point of use and immediately post use.
Various non-destructive testing methods have been developed, including the bubble point test, diffusion test, water intrusion test, and their variations. In conventional non-destructive testing methods, the testing equipment is susceptible to undesirable exposure to various contaminants including hazardous substances, particulates, liquids, and/or biological components. In general, at the beginning of an integrity test, a pressurized gas flows from the testing equipment to the filter device to be tested. At the end of the test, the system is de-energized and a significant amount of venting gas may flow in the direction to the testing equipment, exposing the testing equipment to the risk of contamination. The venting gas may contain residues of the wetting fluid and/or the product if the test is performed after filtration.
Integrity testing instruments are sensitive instruments and contamination of the instruments may disturb the accuracy of measurement. Further, contamination of the testing instruments can be a source of cross-contamination of different filter devices. Therefore, there is a need for apparatuses and methods that can protect the testing instruments from contamination and prevent cross-contamination. There is a general need for apparatuses and methods that can overcome the disadvantages of conventional filter integrity testing.